This invention relates to a process for preparing long chain alkyl aromatic compounds by alkylating an aromatic compound with a relatively long chain alkylating agent employing Lewis-acid promoted amorphous, porous inorganic oxides as alkylation catalysts.
The alkylation of aromatic hydrocarbon with olefin employing a Lewis acid or Friedel-Crafts catalyst, e.g., AlCl.sub.3, BF.sub.3, HF, etc., to provide alkyl aromatic compounds is known in the art. Thus, for example, the alkylation processes described in U.S. Pat. Nos. 2,939,890 and 3,131,230 utilize a catalyst composition containing BF.sub.3 and a BF.sub.3 -modified substantially anhydrous inorganic oxide such as anhydrous gamma-alumina. While both patents disclose a molar ratio of aromatic hydrocarbon to olefin of from 2 to 10 or more, and in some cases up to 20, they further disclose that when the olefin alkylating agent is higher in molecular weight than the pentenes, it is particularly necessary to conduct the alkylation process at the higher end of the aforestated range of aromatic to olefin mole ratio. There is, then, an express, specific recommendation against the use of relatively low aromatic to olefin mole ratios in U.S. Pat. Nos. 2,939,890 and 3,131,230 when the olefin (or functionally equivalent alkylating agent) possesses a greater carbon content than the pentenes.
U.S. Pat. No. 3,173,965 discloses the alkylation of benzene with olefin in the presence of a Friedel-Crafts catalyst, e.g., AlCl.sub.3, AlBr.sub.3, FeCl.sub.3, SnCl.sub.4, BF.sub.3, ZnCl.sub.2, HF, H.sub.2 SO.sub.4, P.sub.2 O.sub.5 and H.sub.3 PO.sub.4, to provide a polyalkylated benzene product of relatively high viscosity index (V.I.), i.e., from 90 to 145, which is useful as a lubricant.
According to U.S. Pat. No. 4,035,308, excess benzene is alkylated with decene dimer in the presence of BF.sub.3 -promoted anhydrous AlCl.sub.3 to provide a monoalkyl benzene product useful as a lubricant or power transmission fluid.
U.S. Pat. No. 4,148,834 describes a two-step alkylation process for preparing di-long chain alkyl aromatic compounds, useful as lubricants, in which aromatic hydrocarbon is alkylated with linear monoolefin in the presence of HF catalyst in a first step and aluminum chloride or aluminum bromide catalyst in a second step.
U.S. Pat. No. 4,691,068 discloses the preparation of long chain monoalkyl aromatics useful in producing detergents, employing a Friedel-Crafts catalyst, e.g., AlCl.sub.3 --HCl, and featuring the recycle of a heavy boiling product fraction to the alkylation reaction.